This time, we'll be reviewing the Ref. PRW-35TLD-7JF, a compact model that fits a wide range of users, even among the Casio Pro Trek series, which is highly popular among mountaineering enthusiasts. This model inherits the Pro Trek's versatility despite its compact 39.7mm case diameter. It's also a first for Casio, featuring a luminous LCD that glows dimly in the dark, providing excellent visibility and a pleasant user experience.
Quartz (photovoltaic). 22 months of operation on a full charge (with power save activated). Biomass plastic case (diameter 44.6mm, thickness 13.0mm). 10 bar water resistance. 88,000 yen (tax included).
Text and Photographs by Shin-ichi Sato
[Article published on January 27, 2025]
Before we get to the impressions, let's review the Pro Trek.
This time, we'll be reviewing the latest model from Casio's outdoor watch brand, Pro Trek, the Ref. PRW-35TLD-7JF. Pro Trek, which launched in 1995, has a history of being popular with mountaineering enthusiasts, with its first model, the Ref. DPX-500, equipped with a "triple sensor." This triple sensor refers to a direction sensor, a barometric pressure (altitude) sensor, and a temperature sensor, and these sensors remain a Pro Trek icon to this day.
The Pro Trek, which boasted these features in an era before smartwatches and was a unique outdoor model from Casio, a manufacturer known for its tough tool watches, was well received by mountain climbing enthusiasts and other outdoor hobbyists, solidifying its image. One proof of this is the fact that Pro Trek watches are now available in outdoor equipment stores.
Furthermore, Pro Trek is supported not only by hobbyists but also by professional alpinists, and as a reflection of this, the company's lineup includes the flagship model "Manaslu," named after Manaslu, one of the 8000-meter peaks, and offering enhanced reliability and functionality.
Impressions of the Ref. PRW-35TLD-7JF
Because of its origins, the Pro Trek is equipped with three sensors not found in ordinary wristwatches, and has a large, robust design to enhance reliability. This styling is characteristic of a tool watch suited to the outdoors, symbolizing its toughness, and was one of the reasons for its popularity. However, it is also true that the size did not fit perfectly on some users' wrists. In particular, it could be said that the size was difficult to match for the increasing number of female mountain climbing enthusiasts and campers in recent years.
It was against this backdrop that the "PRW-35" lineup, which forms the basis of this work, was released. The PRW-35 is a more compact model than previous models, with a case diameter of 44.6mm and a thickness of 13mm, giving it a style that suits a wide range of users. It has also been made lighter; when compared with the previous Ref. PRW-30-1AJF, which weighed 66g, the Ref. PRW-35-7JF weighs in at 45g, a reduction of approximately 30% when compared with the previous Ref. PRW-30-1AJF with a rubber strap.
The Ref. PRW-35TLD-7JF that we will be reviewing this time features a titanium bracelet instead of a rubber strap, adding a new appeal to the Pro Trek, which is often paired with rubber or fabric straps. At 76g, it is heavier than a rubber strap, but it feels light and comfortable to wear.
The resin parts of this watch, such as the case and back cover, are made from biomass plastic, which is expected to contribute to reducing environmental impact. The titanium bracelet and plastic case are an unusual combination, but the metallic texture of the bezel and the silver finish on the entire case give the watch a sense of unity.
The packaging is so good it feels more compact than the actual size suggests.
I personally love the original Casio G-SHOCK, the DW-5600, and the analog model, the GA-2100. These two models are relatively compact even among G-SHOCKs, and this watch's 44.6mm case diameter and 13mm thickness aren't significantly smaller than those two. However, when wearing this watch, it feels more compact than the other two. This is due to the case shape's contours, which give it a distinct look.
In addition, the short lugs and wide range of movement at the bracelet attachment point mean that the watch doesn't float around the back of the lugs, providing a comfortable fit. This should also contribute greatly to the overall compact appearance of the watch. There is ample room for the bracelet to move around the lugs, so even for those with smaller wrists than mine, whose circumference is about 18cm, this comfortable fit will likely be maintained.
In addition to its compact and lightweight construction, the excellent fit distributes the weight, making it comfortable to wear. During the impression period, I felt it adapt to my wrist within a few minutes of wearing it, and after a few hours I barely noticed it. It also fits comfortably in the sleeve, which also contributes to its comfortable fit. These characteristics will help you relax and enjoy the spectacular scenery outdoors, or concentrate on the rugged nature in front of you.
Introducing the main features of the triple sensor
This watch is usually understated, but it has a wealth of features to support you when you need them. Its basic functions include automatic time correction via Multiband 6 radio wave reception, a stopwatch, timer, alarm, world time display, and sunrise and sunset times. With these features, your timekeeping needs will be met.
There are push buttons at the 2 o'clock position for the direction, at the 3 o'clock position for the barometric pressure and temperature, and at the 4 o'clock position for the altitude. Each function can be called up immediately by pressing a button, so there is no stress involved. Although it is simple, let's explain each function in order.
When the function is enabled, the azimuth angle is displayed immediately. I tried it in various situations, and the readings did not fluctuate significantly, even in an environment surrounded by PCs and televisions. As a tricky test, I brought it close to a guitar pickup with an embedded magnet (Alnico 3), and the correct reading was maintained as long as it was about 30 cm away. I suspect that in most cases, the azimuth angle will be displayed without any problems.
The barometric pressure is also displayed quickly, and by monitoring it continuously, you can see that it fluctuates more than expected throughout the day. During the impression period, there were days when the weather changed from light rain to sunny skies, and it was possible to see the barometric pressure rising at those times. This barometric pressure display will be useful when hiking, where the weather can fluctuate greatly and you need to be able to detect those changes as soon as possible. It may also be a useful feature for those whose physical condition is easily affected by changes in barometric pressure. In addition, the watch is equipped with a function that notifies you of sudden changes in barometric pressure, so you can enjoy the benefits of this app without having to keep a close eye on it.
The altitude also changed when moving within a building or on a sloped road. By performing additional operations, it is possible to save the maximum altitude and cumulative ascent, making it possible to keep a log of mountain climbing.
The manual provided by Casio provides detailed information about the meaning of the values and indicators shown by each function, as well as how to adjust and utilize each one. In this review, we were unable to comprehensively test many of the functions, nor were we able to evaluate the camera outdoors, so we recommend that you actually get your hands on the camera and see for yourself how well it performs.
A display that effortlessly displays numerous functions
When it comes to multi-function devices, complex displays can become difficult to read and it can be hard to understand what the current display means. I didn't notice any problems in this regard. The device uses a large LCD, and the main central display is large and clear. The contrast is also high.
Because it has so many functions, it's assumed you have a general understanding of them, but the combination of the central display and indicators (for example, barometric pressure is displayed in hPa) makes it easy to read the information. The dots on the periphery are also cleverly used to indicate direction, show rising or falling barometric pressure trends, and display the time zone, making it intuitively easy to understand. I feel that Casio's handling of the LCD screen is top-class, so users with experience using Casio watches should have no need to worry.
Other usability is also good and I feel it is highly complete.
Another interesting feature was the phosphorescent LCD, which has a phosphorescent sheet at the bottom. When the watch is in a dark place, it glows a faint green, improving visibility. This is the first time Casio has used this technology. According to Casio, if you shine a 200-lumen mountaineering headlamp within 5cm of the watch, the light will remain lit for up to about an hour.
Even without actively shining it, if it's phosphorescent in a bright office, it will glow faintly even on a dimly lit street at night, helping with visibility. LCDs are almost invisible in dark environments, so even though it's a faint light, it makes a big difference whether it's there or not. There's also an LED backlight switch at the 6 o'clock position, and it also has an automatic light-up function that reacts to arm movement, so if you use them appropriately, you shouldn't have to worry about visibility.
It's a bit of a hidden trick, but turning on the LED backlight multiple times makes it glow slightly, helping with visibility. The energy gained from photovoltaic power generation is converted into light and stored in a luminous sheet, improving visibility. It's a very eco-friendly solution.
The controls, which are related to ease of use, are large and have a non-slip surface, making them easy to press. Each button also has a guard on the bottom half to prevent damage to the button and prevent accidental operation. You can really sense Casio's skill in this regard.
When fully charged, this watch can operate for approximately 22 months without solar power generation and in power saving mode. Furthermore, if you place it near a window on a sunny day, it can charge for a day in approximately 24 minutes. However, perhaps due to its large battery capacity to support its many functions, it takes at least 18 hours to fully charge from a completely empty state. However, it does have a battery level indicator, so it seems like it would be easy to manage the charge.
Highly complete, compact design with multiple functions
A large design is advantageous when considering the need to display multiple functions clearly and the inclusion of sensors for those functions. On the other hand, a compact design has many advantages when it comes to everyday use or during activities. This model's appeal lies in its good balance of good visibility and multiple functions, all packed into a compact design. Each function can be accessed smoothly without having to read the manual in detail, and once you have a deep understanding of each function, they will provide ample support to the user. The refined operation and functionality in this area are truly impressive, as you would expect from a Pro Trek and a Casio. The adoption of a luminous LCD is also likely the result of steady refinement.
All in all, this watch is so well-made that Pro Trek enthusiasts can rest assured that it is a good choice. It's also recommended for those who were hesitant about the size of the Pro Trek, as it offers all of its charm in a compact package.
